When I mean "causally connected to" I meant "we could send signals to each other". Most of the universe we can currently see is causally disconnected, in that we can never signal them (the nonzero cosmological constant means they will recede faster than a signal could reach them.)

There could be unlimited volumes of spacetime beyond this horizon. Whether life originates there or not we can never know. There is a finite amount of matter within this horizon, and finitely many chances for life to originate. If OoL is sufficiently unlikely it is unlikely to have happened twice in the volume we can reach.